Walter bobbins



' March 9 1926. 1,576,222

7 w. ROBBINS IGNITION APPARATUS Filed Nov. 23, 1921 20 1 INV NTOR fi/M W ATTORNEY Patented Mar. 9, 1926.

WALTER ROBBINS, OF ST. LOUIS, MISSOURI.

IGNITION APPARATUS.

Application filed November citizen of the United States of America,

residing at the cit of St. Louis, State of Missouri, United tates-of America, have invented a certain new and useful Ignition Apparatus, of which the following is such a full, clear, and exact description as will enable any one skilled in the art to which it appertains to make and use the same, referenee being had to the accompanying drawin s, forming part of this specification.

y invention relates to an ignition apparatus for internal combustion engines and particularly to a mechanically controlled nterrupter mechanism for the primary circuit of the ignition coil.

The ordinar interrupter construction for an ignition system having a normally closed .20 primary circuit comprises a spring controlled lever carrying a movable contact and an engine driven camcooperating 'with said lever to interrupt the primary circuit. At low engine speeds the lever follows the cam surface closely and closes the circuit within the time after break which is predetermined by the cam surface or in other words the time of closed circuit is governed by the speed of the cam and equals the time required for the cam to pass through a definite angle'of rotation.

At high speeds, however, the inertia of the interrupter lever is not overcome with su-fiicient rapidity by the'controlling spring to maintain the relation described and in ertia, causes the interrupter lever to have a greater amplitude of vlbratory movement than at lower sppeds with the result that at high speeds t e time during which the primary ignition circuit remains closed is shortened to a greater extent than proportionally to the speed of cam and the current v in the primary coil, on account of impedance and other factors is unable to reach as high a value as at lower en ine speeds. This condition results in a wea ened secondary spark at high speeds and beyond certain limits in the omission of some of the sparks alto-v gether.

The principal object of my inventlon is to decrease the interval of open circuit with increasing, speed in interrupter apparatus by providing means whereby the distance of travel of the breaker lever between open and closed circuit positions will be the same at all speeds and the necessary angle of ro- 23, 1921. Serial No. 517,188.

tation of the cam during the time between the interruption and re-closing of the ignition circuit be considerably less than in the ordinary interrupter mechanism in which the breaker lever must reverse its direction of travel between opening and reclosing the circuit. Other objects and advantages of my invention lie in the division of the primary circuit interruptions between two sets of contacts thereby lengthening the life and efficiency of the contacts and the provision of a simple mechanical structure for the purpose desired and one which is capable of easy adjustment.

In the accompanying'drawings, Figure 1 1s a diagrammatic view of an interrupter mechanism, embodying my invention and showing the primary and secondary ignition circuits. Figure 2 is a top plan view of one form of mechanism embodying my invention and Figure 3 is a vertical sectional view along the line 33 of Figure 2 and in the direction indicated.

Referring to Figure 1, 1- represents the breaker cam driven by a half time shaft of the engine and 2 is a pivoted interrupter lever or breaker arm having its free end held in contact with the cam by spring 3. The interrupter lever carries contacts 4 and 5 on opposite sides as shown which contacts cooperate with contacts 6 and 7 respectively, these contacts 6 and 7 being carried by flat springs 8 and 9. The travel of each of these contact springs toward the contact lever is limited by the stops 10. The primary ignition circuit comprises the winding 11 of the ignition coil, the battery or other source of current 12, the interrupter lever 2 and either of the contact carrying members 8 and 9, these members being connected in parallel. The secondary 13 of the ignition coil is in circuit with the distributor 14 which distributes the secondary current to the engine spark plugs diagrammatically indicated at 15.

In the mechanical embodiment of my invention shown in Figure 2, the contact carrying springs 8 and 9 are mounted on a conducting block 26 which block is supported on the base plate 16 through which the half time shaft 25 passes. Block 26 is insulated from plate 16 by insulating collar 17. The screw 18 serves to hold the block 26 in position and also for the attachment of one lead from the primary of the ignition coil. The other lead from the primary is connected to breaker arm 2 and may be so connected by attachin it to the pivot of the arm or by groun ing the lead and the pivot.

The breaker arm may be actuated toward the cam either by a flat spring 3 of the type shown in Figure 1 or by a coil spring 21 as shown in Figure 2. Adjustment of the stationary position of the contacts 6 and 7 with respect to the contacts 4 and 5 on the interrupter lever is accomplished in the apparatus of Figure 2 by the screw 22 passing through insulating block 23 supported on the base 16. This screw 22 passes through an opening in the lever 9 and an o ening in the breaker lever 2, the end of t e screw forming the stop for the lever 8 and the v at the other.

nut 24 forming the stop for the lever 9. Suitable lock nuts as shown serve to hold the screw 22 and the nut 24 in adjusted position. The position of the contacts 6 and 7 can thus be adjusted= for proper timing with respect to the contacts on the breaker arm so that the primary circuit will be re-established through one pair of contacts immediately after having been broken The actual time interval of open circuit will be-afi'ected by the shape of the cam, and the adjustment of the stops, screw 22, and nut 24. The illustrated cam is -for an eight cylinder engine but the necessa modification foran engine of two or a mu tiple of two cylinders will be obvious. In the case of engines having one, three or other odd number of cylinders the cam shaft would be driven at engine speed.

It will be noted that in the apparatus described, the distanceof travel of the breaker arm during the interval of open circuit is not afiected by the inertia factor-and is constant at all speeds instead of variable with varying speeds as in the ordinary interrupter. The time of open clrcuit will be decreased with increasing speed due to the fact that the distance. traveled by the breaker arm while in open circuit position remains the same-and its rate of travel increases.

My improved apparatus has further advantages m that the breaking of the primary circuit is divided betweentwo sets of contacts resulting in long life and more reliable action and that the radius of movement of the contacts on the breaker arm may be less type oithan the radius of movement of the eooperat mg contacts with the result that there is a rubbing actionv between contacts.

I am aware that my invention may be embodied in apparatus of specifically different construction than that herein described without departing from the rinciple thereof and I, therefore, do not desire that the sec e of'the invention be limited other than y the appended claims.

Having fully described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. Circuit breaker mechanism for electric ignition systems, comprising two breaker contacts electrically connected, an interrupter member adapted to engage said contacts alternately, and a revolving cam. for actuating said member said cam having a plurality of non-radial engagin surfaces for controlling'the motion of sai member, and said breaker contacts being so arran ed with respect to the interrupter member t at a single non-radial face of the cam controls the interrupter member to cause both its disengagement from one breaker contact and its immediate re-engagement with the other contact through further movement of the interrupter member in the same direction.

2. Circuit breaker mechanism for electric ignition systems, comprising s ring mounted contact members electrica y connected, an interrupter lever extending between the contact members and carrying contacts to co-operate alternately with said contact members, a stop for each contact member limiting its movement toward the interrupter ever, and means adapted to impart vibratory -motion to theinterrupter lever, said means including a revolving cam having a plurality of non-radial engaging surfaces, the contacts on the spring actuated contact members being so positioned with respect to lever carried contacts that engagement of one pair of contacts during contlnuous movement of the lever in one dlrec- -tion is determined by an adjacent portion of the same non-radial surface of the cam which controlled the separation of the other WALTER ROBBINS 

